722 EXPERIMENT STATION EECOED. 



The rock phosphates, particularly the calcined Belgian phosphate, were some- 

 what more effective as fertilizers than the basic slag. 



Submitting these phosphates to repeated extractions with 2 per cent citric 

 acid, it was found that the phosphates were completely soluble in the acid if 

 enough acid was used and the time of extraction sufficiently prolonged, although 

 the ordinary treatment with citric acid showed the phosphoric acid of the rock 

 phosphate to be much less available than that of basic slag. The author, 

 therefore, concludes that the citric acid test is worthless as a means of judging 

 the relative fertilizing value of phosphatic fertilizers. 



Investig-ations on the action of certain soil constituents on monocalciuin 

 phosphate in sandy soils, A. G. Davis {Amer. Fert., 40 (1914), No. 3, pp. S9-Jf1, 

 figs. 2). — To oOO-gm. portions of carefully purified beach sand, were separately 

 added 10-gm. portions each of alumina, ferric oxid, ferrous sulphate, kaolin, 

 lime, and tricalcium phosphate, and to each mixture was added 10 cc. of a 

 solution containing 0.0567 gm. of monocalcium phosphate per cubic centimeter. 

 The mixtures were dried in an oven at 100° C. for 15 hours and then extracted 

 with water. 



The results show that of the substances tested alumina and calcium oxid 

 showed the greatest fixing power for phosphoric acid, kaolin and tricalcium 

 phosphate being less active in this respect, and ferric oxid least of all. The 

 ferric oxid at first fixed the phosphoric acid to a considerable extent, but after 

 a time appeared to liberate it gradually in soluble form. 



The locking up of phosphate fertilizers in Java soils, A. C. De Jongh 

 {Inteiyiat. Mitt. Bodenk., 4 (1914), No. 1, pp. 32-45). — Experiments with soluble 

 and insoluble phosphates on various Java soils are reported, the results in 

 general tending to confirm Hilgard's conclusions that if highly ferruginous soils 

 are fertilized with soluble phosphates " the phosphoric acid is likely to be 

 quickly withdrawn from useful action, so that any excess not promptly taken 

 up by the crop is likely to become inert and useless; . . . that the phosphoric 

 acid tends to combine with the oxids and hydroxids of the trivaleut metals, 

 especially with those of iron, the equivalent aluminic compounds showing the 

 same tendency but to a smaller degree, and that this ferric phosphate is for 

 all practical punioses insoluble and inaccessible to the crop." 



The results, however, did not confirm Hilgard's conclusion " that on ferrugi- 

 nous soils rather difficultly soluble phosphates should be used, such as bone 

 meal and Thomas slag, which are said to be more slowly if at all acted upon 

 by ferric and aluminic hydrates," and tend to discredit Van Bylert's conclusion 

 " that the degree of usefulness of the fertilizer and the relative amount tied 

 up in the soil is materially affected by the phosphate being either in a soluble 

 or in an insoluble state," since the difference in the results obtained with 

 soluble and insoluble phosphates was insignificant. 



Notwithstanding the rapid and extensive fixation of soluble phosphates 

 which took place in certain lateritic soils, it is not, in the author's opinion, to 

 be inferred that moderate application of such phosphates " can not produce a 

 beneficent effect on the crop and good economic results." 



The general conclusion is that the fixation of phosphate fertilizers in soils 

 is chiefly due to certain colloidal compounds of the soil. 



Infl.uence of " crumbing- " of superphosphate and Thomas slag on their 

 action as fertilizers, J. Mikulowski-Pomorski {Ztschr. Landw. Versuchsw. 

 Osterr., 16 (1913), No. 11-12, pp. iW-i055).— Superphosphate and Thomas slag 

 which had been made " crumby " by the addition of gypsum or agar-agar were 

 compared with the same materials in fine-ground condition in pot experiments 

 with oats. 



